1. Field of the Invention
This invention relates to internal combustion engines, and more particularly concerns multi cylinder piston engines suitable for automotive vehicles and capable of shutting down some cylinders while cruising to reduce fuel consumption.
2. Description of the Prior Art
The rising cost of automotive fuel makes it desirable to improve the fuel economy of automotive vehicles. Many improvements in internal combustion engines have been made to maximize fuel economy. One such improvement is the development of an internal combustion engine capable of shutting down some cylinders when the need for power is lesser, such as when cruising on a highway, but is quickly capable of using all cylinders when more power is needed, such as when accelerating or climbing. This type of engine conserves fuel by shutting off the fuel supply to the non-functioning cylinders while keeping all valves open to avoid power drain due to what would have been the compression stroke. Meanwhile power continues to be produced by the remaining functioning cylinders, but with reduced fuel consumption.
Although the above-described improvement results in about 20% savings in fuel, it still has its disadvantages. One disadvantage is that, since all the pistons and connecting rods in this engine are connected to one common crankshaft, the pistons and connecting rods in the non-functioning cylinders continue to undergo reciprocating motion inside these cylinders, resulting in inertial and frictional power losses. The constant pumping of air into and out of the non-functioning cylinders (through the valve openings) also results in additional power loss. If these power losses can be eliminated, the fuel savings should be greater than the 20% currently achieved.
Numerous specialized modifications of multi-cylinder internal combustion engines have earlier been disclosed for achieving various results. The use of two or more separate crankshafts to serve some cylinders relative to the remaining cylinders has been described in U.S. Pat. Nos. 4,170,970; 4,470,379; 5,732,668 and 6,205,972. However, said separate crankshafts generally operate synchronously, and not in selectively alternating manner to accomplish results other than fuel economy.
It is accordingly an object of the present invention to provide a multi-cylinder internal combustion engine for use in an automotive vehicle and having improved efficiency of fuel consumption.
It is a further object of this invention to provide an engine as in the foregoing object which is compatible with automotive vehicles of present design.
It is a still further object of the present invention to provide an engine of the aforesaid nature capable of selectively and periodically deactivating some cylinders by fuel deprivation when their power is not needed.
It is yet another object of this invention to provide an engine of the aforesaid nature wherein the deactivation of said cylinders includes cessation of movement of otherwise moving components associated with said cylinders.
These objects and other objects and advantages of the invention will be apparent from the following description.